Down which is a natural fiber is known to have excellent thermal insulating properties as it is formed of clusters having a plurality of tentacles to which is trapped miniscule air particles. In fact it is considered to be one of the best natural insulation per unit mass and is common in garments for winter outdoor use. Down, in sheet form, as disclosed in my earlier U.S. Pat. No. 6,025,041 provides, in sheet form, constant thermal value of the down throughout its insulating layer while retaining its shape and loft and is lightweight. It is an excellent product for use in the fabrication of articles of apparel.
When down is wet, such as when washing a down filled garment, the down becomes damaged and its insulating efficiency is reduced due to many factors, such as trapping humidity, clumping and trapping cleaning agents such as soap and detergents which are damaging to the down clusters. To overcome these deficiencies synthetic fibers have been used but its disadvantages such as being heavier than down, being bulky and unstable and requiring additional needlework on the article of apparel to stabilize the loose synthetic fibers. Needlework produce cold spots between the outer fabric shell of the garment and its inner liner and adds to fabrication costs.
Thermally insulated articles of apparel, sleeping bags, boots, gloves and other thermally insulating articles to keep a person, or parts of a person warm, are well known in the art. For different climatic conditions, and taking for example a jacket, coat or vest as an article of apparel, it is common for a person to have a different one of such articles to wear to adapt for different climatic periods of the year as the temperature changes from hot to cold and this particularly so in regions which experience four seasons. Also, in certain regions climatic conditions can vary abruptly within a season and it becomes cumbersome, uncomfortable and costly to have to change an article of apparel for short duration of time due to severe temperature fluctuations.
It is also known in the art to fabricate coats and jackets with detachable inner insulating fabric cloths which are attached inside the coat or jacket over the inner liner by the use of button or zipper fasteners to adapt the article to changing weather conditions. These insulating cloths are made of fabric material, such as wool, heavy fabrics, and are placed in direct contact with the wearer person. They are also exposed to outside elements and become soiled and require periodic washing which could cause shrinkage and difficult to install. They also have a low thermal insulation value which provide warmth within a limited temperature range which is not sufficient for use in very cold weather regions where there is snowfall and the temperature drops below freezing. These insulating cloths are also not interchangeable with like cloths having different thermal insulating values. A further disadvantage of such insulating cloths is that if they are secured by zippers and when the zipper breaks, they are no longer attachable until if the zipper repaired. Also, during the repair period the article of apparel is not utilized. This is an inconvenience to the user person and in many cases the insulating cloth is simply discarded.
It is further known in the prior art to provide articles of apparel and duvet covers with pockets in which one can insert hot packs or cold packs to modify the insulating value of the article or to modify its temperature for added comfort. Many of these pouches are bulky and appear as patch work on the article and most packs quickly loose their efficiency and do not provide adequate insulation. Also, they are bulky and distort the fashionable appearance of the garment.
It would be advantageous to be able to quickly convert an article of warmth to make it adaptable to changing weather conditions. This has not been made possible for several reasons in that most articles of warmth, such as articles of apparel are constructed for seasonal use. A winter article of apparel usually contains loose thermal insulation which is stabilized from movement by stitch patterns across the outer fabric shell and the inner liner material to retain the loose insulation permanently captive in stitched pockets to arrest its displacement between the outer shell and inner liner fabrics when the article is in use or being washed. Therefore, most insulated articles of apparel are fabricated for seasonal use and it is therefore necessary to change articles of apparel as the seasons change to adapt it to the changing weather and this is costly to the consumer.
Another disadvantage with articles of warmth such as articles of apparel and sleeping bags which contain loose insulation, is that when these are washed the loose insulation often retains moisture for long periods of time and therefore requiring long drying time in a dryer machine. They also retain detergent which is damaging to the down. Also, the loose insulation has a tendency to form clumps and thereby giving a worn appearance to the article thereby reducing its useful life. Further, the loose insulation in such articles of apparel or sleeping bags gives volume to the article occupying space in a washing or drying machine. It is desirable to overcome this further problem for such articles manufactured with such type of thermal insulation.
A still further disadvantage of articles of warmth is that they cannot adapt to weather changing conditions, such as rain, cold and short lived temperature swings without changing the article of warmth for a different article which is more comfortable to the changed weather. With respect to articles of apparel wherein gel packs or heat releasing packs are inserted in pocket of the article of apparel, a disadvantage of these is that these packets gradually loose their efficiency within a few hours and do not provide their intended result for a long period of time, usually loosing all of their efficiency within four to five hours of use. Also, many of these articles of warmth provide pockets on the outer surface of the outer shell of the article of warmth making it unpleasant to the eye. Still further, the outer shell is often not pleasing to the eyes for all seasonal use.